$ { {-4} \times \left[\begin{array}{rr}{2} & {4} \\ {1} & {4} \\ {3} & {0}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{-4}\times{2} & {-4}\times{4} \\ {-4}\times{1} & {-4}\times{4} \\ {-4}\times{3} & {-4}\times{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-8} & {-16} \\ {-4} & {-16} \\ {-12} & {0}\end{array}\right]}$